This handsome spinet was in the auction of Byrnes, Chester, on November 20. Christian Shean was working in London from c. 1753. By 1760 he had moved to Edinburgh, where he died in 1794. Five spinets by him are recorded in Boalch-Mould Online; this could be a sixth. One is in the Edinburgh Collectons, dated 1782, and inscribed 'Christian Shean from London'. This one appears to say simply 'London', which could imply that it was made not later than 1760. But it is in a beautiful mahogany case with the 'harpsichord' compass of FF, GG - f3, typical of the later British spinets, and suggesting a date in the 178os.
I have requested more details, and will add them as soon as I can.
The auctioneer's estimate is £300 - £500 - it did rather better than that at £6,800.
Looks pretty good to me; the auctioneer has no specialist knowledge, but makes it clear that at least tuning and regulation are necessary!
All images by, and by courtesy of, Byne's Fine Art Auctioneers